Strain reliefs are generally used in electrical components which have cords that extend through an opening in the case or housing of a component. If left unprotected, the cord would soon fray due to the friction of rubbing against the case opening. Strain relief is also provided to relieve bending strains in the cord as it bends at or near its connection with the opening.
Typical applications include using a knot on the cable to prevent it from pulling through and opening, hold downs inside an enclosure, or an over-mold that is captured between two sections of an enclosure. However, typical applications do not apply where the enclosure is very small or if the opening in the enclosure is not at intersection of the sections of the enclosure.